Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
from collections import Counter
H, W = map(int, input().split())
s = [list(input()) for _ in range(H)]
t = [[-1]*W for _ in range(H)]
q = deque([[0,0]])
t[0][0] = 0
while len(q) > 0:
  qq = q.popleft()
  dh = [-1,0,1,0]
  dw = [0,1,0,-1]
  for i in range(4):
    h = qq[0] + dh[i]
    w = qq[1] + dw[i]
    if 0 <= h < H and 0 <= w < W:
      if s[h][w] == "#" or t[h][w] != -1: continue
      t[h][w] = t[qq[0]][qq[1]] + 1
      q.append([h,w])

X = 0
for i in range(H):
  c = Counter(s[i])
  X += c["."]
if t[H-1][W-1] == -1:
  print(-1)
else:
  print(X-1-t[H-1][W-1])